Cher -- You're Never Too Old For Nipple Pasties

67-year-old Cher is still super proud of her boobs ... and proved it by sportin' a pair of nipple pasties this week at a concert in Boston.

Cher -- who also rocked a pink wig, pink lip gloss at her Dressed to Kill tour -- seemed extra perky that night ... and also broke out her old low-plunging black onsie from her "If I Could Turn Back Time" video.

As for the nipple pasties ... one question -- doesn't it hurt to take those things off??